EFFECT OF LUNG-VOLUME REDUCTION SURGERY IN A RABBIT MODEL OF BULLOUS LUNG-DISEASE

Clinical use of staple lung volume reduction surgery (LVRS) has prolif erated for treatment of emphysema despite limited data regarding effic acy or optimal techniques. Recent studies in animal models of obstruct ive lung disease describe the decrease in lung compliance and increase in airway support as mechanisms of an improvement in pulmonary functi ons analogous to human data. We describe contrasting results in an ani mal model of bullous lung disease with a mixed but predominantly restr ictive pattern of lung disease. Mixed restrictive and bullous lung dis ease was induced in 17 New Zealand white rabbits with iv Sephadex bead s and endotracheally instilled carrageenan. Unilateral stapled lung vo lume reduction surgery was performed at 5 weeks postinduction of emphy sema on the right lower lobe by lateral thoracotomy using a pediatric stapler. Static trans-pleural pressures were measured at 60, 40, and 2 0 cm(3) inflation at preinduction (baseline), pre- and postoperatively , and 1 week postoperatively in anesthetized animals. Lungs were then harvested en bloc and examined histopathologically. The effects of vol ume reduction surgery on static lung compliance, lung conductance, ana forced expiratory flows (FEF) were assessed. Five weeks after inducti on of lung disease, the animals had no significant change in static co mpliance and forced expiratory volume in 0.5 s (FEV0.5) or lung conduc tance compared to baseline. Immediately following LVRS, the animals sh owed a significant decrease in static compliance, FEV0.5, and conducta nce. One week postoperatively, compliance increased to approximately b aseline levels along with a slight increase in FEFs and conductance to ward preoperative levels.:Histology examination revealed restrictive a nd bullous lung disease. Thus, we have demonstrated the feasibility of using an animal model for evaluation of volume reduction therapy for restrictive-obstructive lung disease. Physiologically, this model show ed decrease conductance and decreased forced expiratory flows followin g lung volume reduction despite increased recoil. This is in contrast to increased conductance and flows seen in humans with severe emphysem a following surgery and suggests that current criteria excluding patie nts with a significant restrictive component to their lung disease fro m LVRS surgery may be justified.